The invention relates to a high-power cathode system for producing layers of different target materials on a substrate.
High-power cathode systems with planar or convex target plates are known. They are also called "magnetrons". A magnetron is described, for example, in DE-OS No. 3,047,113.
In a magnetron, at least one magnetic field generator which can be in the form of an electromagnet or a grouping of permanent magnets is behind the target plate. The individual poles or pole shoes of the magnetic field generator are disposed one inside the other in a closed figure such as a ring, rectangle or oval so that the poles of the one polarity are on the outside and those of the other polarity are on the inside of the figure. This results in a three-dimensional tunnel of arcuate lines of magnetic force arranged about the figure and having their roots in the target surface. The result is a concentration of the glow discharge form the cathode system target in an area inside the tunnel and, consequently, a considerable increase in the probability of the collision of electrons and ions therein. This increases the rate of the sputtering of the target material, and hence the rate of condensation on an adjacent substrate, for example by a factor of ten to twenty. For this reason, such magnetrons are also referred to as high-power cathodes.
Layers of different target materials have been made by arranging a corresponding number of magnetrons, each consisting of a magnetron base body and a magnetic field generator, but having a target plate of a different material, in a row, one after another, and moving a substrate successively under all of the magnetrons. In this manner, a succession of layers of the individual target materials has been formed. One especially well-known application is the production of infrared-reflecting window glass in which the first layer is in adhesivizer, the second layer, the actual infrared-reflecting layer, and the third layer, a protection and interference layer. These layers were, however, strictly, separate from one another. The individual layers had no zones of transition therebetween, so that the strength of adhesion between the individual layers was not sufficient for a number of applications in which layers are subjected to great mechanical stress.
It is also known through DE-OS No. 2,243,708 to construct a magnetron system with a target in the form of a circular plate and a circular ring surrounding the latter at a distance therefrom, or from two semicircular disks with a gap between them. A single tunnel of lines of magnetic force extends over both of these target or cathode parts. The cathode parts, however, are also supplied with high-frequency alternating current in a way which constantly gives them different potentials relative to one another so that the gap between them is essential for insulation. Furthermore, in the patent publication, the two cathode parts consist of the same material, so that neither a disclosure nor a suggestion exists of producing layers with a zone of transition therebetween.